1. Field of the Invention
The present invention relates to an emulsifier for an asphalt emulsion which comprises a monoamine having an aliphatic hydrocarbon group having 8 to 22 carbon atoms, a diamine having an aliphatic hydrocarbon group having 8 to 22 carbon atoms and a polyamine having an aliphatic hydrocarbon group having 8 to 22 carbon atoms and containing 3 to 6 amino groups, at a specific mixing ratio.
2. Description of Prior Arts
As emulsifiers for the production of cationic asphalt emulsions, there have heretofore been used, for example, beef tallow propylene diamine, hardened beef tallow propylene diamine, ethylene oxide adducts thereof, 1-aminoethyl-2-heptadecenylimidazoline-2, stearyltrimethyl ammonium chloride and aminated lignin. Recently, however, the asphalts used and the traffic environments have changed, and development of new emulsifiers coping with these changes has been desired. More specifically, the importance of an asphalt emulsion as a binder for treating the pavement surface has been increasing but with the increase of the traffic volume, an asphalt having a reduced penetration, namely a hard asphalt, has been desired. Conventional straight asphalt formed as a distillation residue of crude oil is now being substituted by an asphalt obtained by softening with a flux a very hard asphalt formed by the propane deasphalting method. An emulsifier applicable to these varying materials is required to have a certain latitude in the emulsifying capacity. More specifically, it has been clarified that an emulsifier comprising a plurality of emulsifier components is preferable to an emulsifier composed of a single component. However, an emulsifier composition having an excellent emulsifying capacity to the above-mentioned asphalt having a low penetration has not been developed.